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commandlinefu.com is the place to record those command-line gems that you return to again and again.

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Every new command is wrapped in a tweet and posted
to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning,
there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

This makes an alias for a command named 'busy'. The 'busy' command opens a random file in /usr/include to a random line with vim. Drop this in your .bash_aliases and make sure that file is initialized in your .bashrc.

This function is used to sort selected lines of a text file to the end of that file. Especially useful in cases where human intervention is necessary to sort out parts of a file. Let's say that you have a text file which contains the words

rough

slimy

red

fluff

dough

For whatever reason, you want to sort all words rhyming with 'tough' to the bottom of the file, and all words denoting colors to the top, while keeping the order of the rest of the file intact.

'$EDITOR' will open, showing all of the lines in the given file, numbered with '0' padding. Adding a '~' to the beginning of the line will cause the line to sort to the end of the file, adding '!' will cause it to sort to the beginning.

This command loops over all of the processes in a system and creates an associative array in awk with the process name as the key and the sum of the RSS as the value. The associative array has the effect of summing a parent process and all of it's children. It then prints the top ten processes sorted by size.

This is different that `who` in that who only cares about logged-in users running shells, this command will show all daemon users and what not; also users logged in remotely via SSH but are running SFTP/SCP only and not a shell.

If you need to randomize the lines in a file, but have an old sort commands that doesn't support the -R option, this could be helpful. It's easy enough to remember so that you can create it as a script and use that.

It ain't real fast. It ain't safe. It ain't super random. Do not use it on untrusted data. It requires bash for the $RANDOM variable to work.

Improvement of the command "Find Duplicate Files (based on size first, then MD5 hash)" when searching for duplicate files in a directory containing a subversion working copy. This way the (multiple dupicates) in the meta-information directories are ignored.

Can easily be adopted for other VCS as well. For CVS i.e. change ".svn" into ".csv":

Comcast is an ISP in the United States that has started hijacking DNS requests as a "service" for its customers. For example, in Firefox, one used to be able to do a quick "I'm Feeling Lucky" Google search by typing a single word into the URL field, assuming the word is not an existing domain when surrounded by www.*.com. Comcast customers never receive the correct NX (non-existent domain) error from DNS. Instead, they are shown a page full of advertising. There is a way to "opt out" from their service, but that requires having the account password and the MAC address of your modem handy. For me, it was easier just to set static DNS servers. But the problem is, which ones to choose? That's what this command answers. It'll show you the three _non-hijacked_ Comcast DNS servers that are the shortest distance away.

Perhaps you don't have Comcast (lucky you!), but hopefully this command can serve as an example of using netselect to find the fastest server from a list. Note that, although this example doesn't show it, netselect will actually perform the uniq and DNS resolution for you.